Coupler lock



FIG. 1 is a perspective view of a coupler lock showing my new design;

FIG. 2 is front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a first side view thereof;

FIG. 5 is a second side view thereof;

FIG. 6 is a top side view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines in the figures are included for the purpose of illustrating portions of a coupler lock and form no part of the claimed design. 

CLAIM The ornamental design for a coupler lock, as shown and described. 